ZIF-derived zinc decorated cobalt nanoparticles for efficient oxygen reduction and Zn-air batteries

Abstract

Cobalt-nitrogen-doped carbon (Co-N-C) materials are regarded as promising candidates to replace Pt-based catalysts for oxygen reduction reaction (ORR). Introducing Zn species with a small electronegativity to form Co/Zn-N-C catalysts could promote the electron transfer and enhance the ORR activity. Herein, we report Zn-anchored Co nanoparticles encapsulated in porous N-doped carbon ((Zn, Co)/NC) derived from Zn/Co-ZIF-67. Compared with the catalyst without Zn, (Zn, Co)/NC exhibits higher ORR catalytic activities in alkaline and acidic media with outstanding methanol tolerance and stability. The assembled Zn-air battery used (Zn, Co)/NC presents higher peak power density (186 mW·cm−2) and specific capacity (807 mAh·g−1) than those of Pt/C. The density functional theory (DFT) calculations demonstrate Zn atoms on Co NPs induce more charges transfer from inner metal NPs to carbon shell, leading to more charges accumulation around N-C active sites to activate O2 and reducing the energy barrier of (Zn, Co)/NC for ORR.